Electromagnetic Waves Flashcards
describe what is meant by electromagnetic waves.
transverse waves that transfer energy from to source of the waves to an absorber
state the electromagnetic spectrum from long wavelength and low frequency to short wavelength and high frequency
radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays
state some properties of electromagnetic waves
different substances may absorb, transmit, refract or reflect electromagnetic waves in ways that vary with wavelength
some effects, for example refraction, are due to the difference in velocity of the waves in different substances
state some properties of radio waves
- they can be produced by oscillations in electrical circuits
- when radio waves are absorbed, they may create an alternating current with the same frequency as the radio wave itself, so they can themselves induce oscillations in an electrical circuit
state what happens when there are changes in atoms and in the nuclei of atoms
it can result in the electromagnetic waves being generated or absorbed over a wide frequency range
gamma rays originate from changes in the nucleus of an atom
describe the effects of waves on human body tissue
UV waves, x-rays and gamma rays can have hazardous effects on human body tissue - the effects depend on the type of radiation and the size of the dose
UV waves can cause skin to age prematurely and increase the risk of skin cancer
x-rays and gamma rays are ionising radiation that can cause the mutation of genes and cancer
state what is meant by radiation dose
a measure of the risk of harm resulting from an exposure of the body to the radiation
give some uses of electromagnetic waves
radio waves - television and radio
microwaves - cooking food, satellite communications
infrared - cooking food, infrared cameras
visible light - fibre optic communications
UV - sun tanning, energy efficient lamps
x-rays and gamma rays - medical imaging and treatments
